Biology subjects

Mews, P.

Publications and source records attributed to Mews, P..

8 recordsLinked to original sources

bioRxiv2026

Bile Acids Regulate Accumbal Cholinergic Circuitry and Dopamine Release through TGR5 Activation

BackgroundFatty foods and alcohol (i.e., ethanol) produce strong reinforcing effects, in part by altering cholinergic interneuron (CIN) activity and tonic dopamine (DA) release within the nucleus accumbens (NAc). Ethanol and fatty foods also both stimulate hepatic and possibly local brain bile acid (BA) synthesis, which raises the possibility that BAs may act as a common upstream regulator of these substances shared mesolimbic effects. MethodsThe current study investigated whether BAs can directly alter mesolimbic activity. Electrophysiological data from acute mouse brain slices was collected to assess BA effects on NAc CIN firing, as well as on excitatory and inhibitory postsynaptic CIN inputs. Bile effects on NAc DA release and clearance rates were measured through voltammetry. ResultsWe found that low concentrations of a 1:1 mixture of BAs cholic acid (CA) and deoxycholic acid (DCA; 1-10 M) increased CIN firing rate, whereas high BA concentrations (1-10 mM) decreased CIN firing. We further demonstrated that BA-induced excitatory effects on CIN firing are independently mediated by at least two mechanisms: Takeda G-protein-coupled receptor 5 (TGR5) activation and suppression of inhibitory CIN currents. Additionally, our results indicate that BAs modulate inhibitory input in a complex manner, reducing frequency at low concentrations, but increasing at high concentrations, and increasing amplitude at low concentrations current amplitude, and the distribution of postsynaptic current amplitude sizes across concentrations. Finally, our voltammetry data indicate that while low BA concentrations enhance NAc DA release without affecting DA uptake, high BA concentrations robustly inhibit accumbal DA release. ConclusionOur findings provide evidence that BAs exert direct modulatory effects on neural activity in the striatum.

neuroscience↗

bioRxiv2024

Cocaine-Induced Gene Regulation in D1 and D2 Neuronal Ensembles of the Nucleus Accumbens Revealed by Single-Cell RNA Sequencing

Cocaine use disorder is characterized by persistent drug-seeking behavior and a high risk of relapse, driven by lasting molecular and circuit adaptations in the nucleus accumbens. To explore the transcriptomic changes underlying these alterations, we employed fluorescence-activated nucleus sorting coupled with single-nucleus RNA sequencing to analyze D1 and D2 medium spiny neurons in this brain region of male mice subjected to acute cocaine exposure or to prolonged withdrawal from repeated cocaine exposure without or with an acute cocaine rechallenge. This approach allowed us to precisely delineate and contrast transcriptionally distinct neuronal subpopulations[boxh]or ensembles - across various treatment conditions. We identified significant heterogeneity within both D1 and D2 MSNs, revealing distinct clusters with unique transcriptional profiles. Notably, we identified a discrete D1 MSN population characterized by the upregulation of immediate early genes, as well as another group of D1 MSNs linked to prolonged withdrawal, uncovering novel regulators of withdrawal-related transcriptome dynamics. Our findings provide a high-resolution transcriptomic map of D1 and D2 MSNs, illustrating the dynamic changes induced by cocaine exposure and withdrawal. These insights into the molecular mechanisms underlying cocaine use disorder highlight potential targets for therapeutic intervention aimed at preventing relapse.

neuroscience↗

bioRxiv2024

Transcriptional characterization of cocaine withdrawal versus extinction within nucleus accumbens

Substance use disorder is characterized by a maladaptive imbalance wherein drug seeking persists despite negative consequences or drug unavailability. This imbalance correlates with neurobiological alterations some of which are amplified during forced abstinence, thereby compromising the capacity of extinction-based approaches to prevent relapse. Cocaine use disorder (CUD) exemplifies this phenomenon in which neurobiological modifications hijack brain reward regions such as the nucleus accumbens (NAc) to manifest craving and withdrawal-like symptoms. While increasing evidence links transcriptional changes in the NAc to specific phases of addiction, genome-wide changes in gene expression during withdrawal vs. extinction (WD/Ext) have not been examined in a context- and NAc-subregion-specific manner. Here, we used cocaine self-administration (SA) in rats combined with RNA-sequencing (RNA-seq) of NAc subregions (core and shell) to transcriptionally profile the impact of experiencing withdrawal in the home cage or in the previous drug context or experiencing extinction training. As expected, home-cage withdrawal maintained drug seeking in the previous drug context, whereas extinction training reduced it. By contrast, withdrawal involving repetitive exposure to the previous drug context increased drug-seeking behavior. Bioinformatic analyses of RNA-seq data revealed gene expression patterns, networks, motifs, and biological functions specific to these behavioral conditions and NAc subregions. Comparing transcriptomic analysis of the NAc of patients with CUD highlighted conserved gene signatures, especially with rats that were repetitively exposed to the previous drug context. Collectively, these behavioral and transcriptional correlates of several withdrawal-extinction settings reveal fundamental and translational information about potential molecular mechanisms to attenuate drug-associated memories.

neuroscience↗

bioRxiv2023

Shared and divergent transcriptomic regulation in nucleus accumbens D1 and D2 medium spiny neurons by cocaine and morphine

Substance use disorders (SUDs) induce widespread molecular dysregulation in the nucleus accumbens (NAc), a brain region pivotal for coordinating motivation and reward. These molecular changes are thought to support lasting neural and behavioral disturbances that promote drug-seeking in addiction. However, different drug classes exert unique influences on neural circuits, cell types, physiology, and gene expression despite the overlapping symptomatology of SUDs. To better understand common and divergent molecular mechanisms governing SUD pathology, our goal was to survey cell-type-specific restructuring of the NAc transcriptional landscape in after psychostimulant or opioid exposure. We combined fluorescence-activated nuclei sorting and RNA sequencing to profile NAc D1 and D2 medium spiny neurons (MSNs) across cocaine and morphine exposure paradigms, including initial exposure, prolonged withdrawal after repeated exposure, and re-exposure post-withdrawal. Our analyses reveal that D1 MSNs display many convergent transcriptional responses across drug classes during exposure, whereas D2 MSNs manifest mostly divergent responses between cocaine and morphine, with morphine causing more adaptations in this cell type. Utilizing multiscale embedded gene co-expression network analysis (MEGENA), we discerned transcriptional regulatory networks subserving biological functions shared between cocaine and morphine. We observed largely integrative engagement of overlapping gene networks across drug classes in D1 MSNs, but opposite regulation of key D2 networks, highlighting potential therapeutic gene network targets within MSNs. These studies establish a landmark, cell-type-specific atlas of transcriptional regulation induced by cocaine and by morphine that can serve as a foundation for future studies towards mechanistic understanding of SUDs. Our findings, and future work leveraging this dataset, will pave the way for the development of targeted therapeutic interventions, addressing the urgent need for more effective treatments for cocaine use disorder and enhancing the existing strategies for opioid use disorder.

neuroscience↗

bioRxiv2022

Cell-Type-Specific Epigenetic Priming of Gene Expression in Nucleus Accumbens by Cocaine

A hallmark of addiction is the ability of drugs of abuse to trigger relapse after periods of prolonged abstinence. Here, we describe a novel epigenetic mechanism whereby chronic cocaine exposure causes lasting chromatin and downstream transcriptional modifications in the nucleus accumbens (NAc), a critical brain region controlling motivation. We link prolonged withdrawal from cocaine to the depletion of the histone variant H2A.Z, coupled to increased genome accessibility and latent priming of gene transcription, in D1 dopamine receptor-expressing medium spiny neurons (D1 MSNs) that relates to aberrant gene expression upon drug relapse. The histone chaperone ANP32E removes H2A.Z from chromatin, and we demonstrate that D1 MSN-selective Anp32e knockdown prevents cocaine-induced H2A.Z depletion and blocks cocaines rewarding actions. By contrast, very different effects of cocaine exposure, withdrawal, and relapse were found for D2-MSNs. These findings establish histone variant exchange as an important mechanism and clinical target engaged by drugs of abuse to corrupt brain function and behavior.

molecular biology↗

bioRxiv2022

Targeting acetyl-CoA metabolism attenuates the formation of fear memories through reduced activity-dependent histone acetylation

Histone acetylation is a key component in the consolidation of long-term fear memories. Epigenetic enzymes involved in histone acetylation, including histone acetyltransferases and deacetylases, have been put forward as potential pharmacological targets in the treatment of pathological fear memories, such as those that underlie post-traumatic stress disorder (PTSD). However, these enzymes typically play a ubiquitous role in gene regulation, which precludes the clinical use of systemic manipulations. Recently, we have found that a nuclear-localized metabolic enzyme, Acetyl-coA synthetase 2 (Acss2), modulates histone acetylation during learning and memory. Loss of Acss2 is well-tolerated in mice, with no impact on general health or baseline behavior. Here, we show that an Acss2 null mouse model shows reduced acquisition of long-term fear memories in assays of contextual and cued fear conditioning. We find that loss of Acss2 leads to consolidation-specific reductions in both histone acetylation and the expression of critical learning and memory-related genes in the dorsal hippocampus. Further, we show that systemic administration of blood-brain-barrier (BBB)-permeable Acss2 inhibitors during the consolidation window reduces fear memory formation in mice and rats, and also reduces anxiety in a predator-scent-stress (PSS) paradigm. Our findings suggest that Acss2 plays a critical role in the formation of fear memories, and represents a potential pharmacological target in the treatment of PTSD.

neuroscience↗

bioRxiv2022

Transcriptional control of nucleus accumbens neuronal excitability by Retinoid X Receptor Alpha tunes sensitivity to drug rewards

The complex nature of the transcriptional networks underlying addictive behaviors suggests intricate cooperation between diverse gene regulation mechanisms that go beyond canonical activity-dependent pathways. Here we implicate in this process a novel nuclear receptor transcription factor, Retinoid X Receptor Alpha (RXR), which we identified bioinformatically as associated with addiction-like behaviors. In the nucleus accumbens (NAc) of male and female mice, we show that, while its own expression remains unaltered after cocaine exposure, RXR controls plasticity- and addiction-relevant transcriptional programs in both dopamine receptor D1- and D2-expressing medium spiny neurons, which in turn modulate intrinsic excitability and synaptic activity of these NAc cell types. Behaviorally, bidirectional viral and pharmacological manipulation of RXR regulates drug reward sensitivity in both non-operant and operant paradigms. Together, this study demonstrates a key role for NAc RXR in promoting drug addiction, and paves the way for future studies of rexinoid signaling in psychiatric disease states.

neuroscience↗

bioRxiv2018

Zfp189 Mediates Stress Resilience Through a CREB-Regulated Transcriptional Network in Prefrontal Cortex

Stress resilience involves numerous brain-wide transcriptional changes. Determining the organization and orchestration of these transcriptional events may reveal novel antidepressant targets, but this remains unexplored. Here, we characterize the resilient transcriptome with co-expression analysis and identify a single transcriptionally-active uniquely-resilient gene network. Zfp189, a previously unstudied zinc finger protein, is the top network key driver and its overexpression in prefrontal cortical (PFC) neurons preferentially activates this network, alters neuronal activity and promotes behavioral resilience. CREB, which binds Zfp189, is the top upstream regulator of this network. To probe CREB-Zfp189 interactions as a network regulatory mechanism, we employ CRISPR-mediated locus-specific transcriptional reprogramming to direct CREB selectively to the Zfp189 promoter. This single molecular interaction in PFC neurons recapitulates the pro-resilient Zfp189-dependent downstream effects on gene network activity, electrophysiology and behavior. These findings reveal an essential role for Zfp189 and a CREB-Zfp189 regulatory axis in mediating a central transcriptional network of resilience.

neuroscience↗